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01-03-2011, 11:42 AM
Nuclear.ppt (Size: 3.73 MB / Downloads: 255)
Nuclear Power Today
• Provides almost 20% of world’s electricity (8% in U.S.)
• 69% of U.S. non-carbon electricity generation
• More than 100 plants in U.S.
– None built since the 1970s
• 200+ plants in the Europe
– Leader is France
• About 80% of its power from nuclear
Early History of Nuclear Power in the U.S.
• After World War II, development of civilian nuclear program
• Atlantic Energy Act of 1946
• 1954: first commercial nuclear power program
• “It is not too much to expect that our children will enjoy in their homes [nuclear generated] electrical energy too cheap to meter.”
• Secret government project and implimentation to create atomic weapons during World War II
• After the war, the government encouraged “the development of nuclear energy for peaceful civilian purposes.”
• This led to the technology used in nuclear plants today
• Atomic Energy Commission (AEC) established by Congress in 1946 as part of the Atomic Energy Act
• AEC authorized the construction of Experimental Breeder Reactor I ( EBR-1) at a site in Idaho in 1949
• in August of 1951, criticality (a controlled, self-sustained, chain reaction) was reached using uranium
• A football sized core was created and kept at low power for four months until December 20, 1951
• power was gradually increased until the first usable amount of electricity was generated, lighting four light bulbs and introducing nuclear generated power for the first time
• In 1953, the EBR-1 was creating one new atom of nuclear fuel for every atom burned, thus the reactor could sustain its own operation
• With this creation of new cores, enough energy was created to fuel additional reactors
• A few years later, the town of Arco, Idaho became the world's first community to get its entire power supply from a nuclear reactor
• This was achieved by temporarily attaching the town’s power grid to the reactor’s turbines
Atoms for Peace
• Began in 1953 and was designed by Eisenhower specifically to promote peaceful, commercial applications of atomic energy after the Manhattan Project and atomic bombings on Japan
• Public support for nuclear energy grew, federal nuclear energy programs shifted their focus to advancing reactor technologies
• With this came the support of utility companies, which saw nuclear energy as a cheap and environmentally safe alternative energy choice
Shippingport Atomic Power Station
• Department of Energy and the Duquesne Light Company broke ground in Shippingport, Pennsylvania in 1954 for the first commercial electric-generating station in the U.S. to use nuclear energy
• Opened on May 26, 1958, as part of Eisenhower’s “Atoms for Peace” program
• Three years later, it began supplying electricity for the Pittsburgh area
• It was by far the world’s largest commercial nuclear power plant, surpassing those already in place in the Soviet Union and Great Britain
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03-03-2011, 12:15 PM
nuclear(2).ppt (Size: 165 KB / Downloads: 103)
Nuclear fuel is any material that can be consumed to derive nuclear energy. The most common type of nuclear fuel is fissile elements that can be made to undergo nuclear fission chain reactions in a nuclear reactor
The most common nuclear fuels are 235U and 239Pu. Not all nuclear fuels are used in fission chain reactions
When a neutron strikes an atom of uranium, the uranium splits ingto two lighter atoms and releases heat simultaneously.
Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments
NUCLEAR CHAIN REACTIONS
A chain reaction refers to a process in which neutrons released in fission produce an additional fission in at least one further nucleus. This nucleus in turn produces neutrons, and the process repeats. If the process is controlled it is used for nuclear power or if uncontrolled it is used for nuclear weapons
U235 + n → fission + 2 or 3 n + 200 MeV
If each neutron releases two more neutrons, then the number of fissions doubles each generation. In that case, in 10 generations there are 1,024 fissions and in 80 generations about 6 x 10 23 (a mole) fissions.
A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an explotion.
Control rods made of a material that absorbs neutrtons are inserted into the bundle using a mechanism that can rise or lower the control rods.
. The control rods essentially contain neutron absorbers like, boron, cadmium or indium.
Steam generators are heat exchangers used to convert water into steam from heat produced in a nuclear reactor core.
Either ordinary water or heavy water is used as the coolant.
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical
Various high-performance alloys and superalloys have been used for steam generator tubing.
The coolant pump pressurizes the coolant to pressures of the orderof 155bar.
The pressue of the coolant loop is maintained almost constant with the help of the pump and a pressurizer unit.
Steam coming out of the turbine, flows through the condenser for condensation and recirculated for the next cycle of operation.
The feed pump circulates the condensed water in the working fluid loop.
Condenser is a device or unit which is used to condense vapor into liquid.
The objective of the condenser are to reduce the turbine exhaust pressure to increase the efficiency and to recover high qyuality feed water in the form of condensate & feed back it to the steam generator without any further treatment.
Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere.
Water cirulating throughthe codeser is taken to the cooling tower for cooling and reuse
Nuclear power generation does emit relatively low amounts of carbon dioxide (CO2). The emissions of green house gases and therefore the contribution of nuclear power plants to global warming is therefore relatively little.
This technology is readily available, it does not have to be developed first.
It is possible to generate a high amount of electrical energy in one single plant
The problem of radioactive waste is still an unsolved one.
High risks: It is technically impossible to build a plant with 100% security.
The energy source for nuclear energy is Uranium. Uranium is a scarce resource, its supply is estimated to last only for the next 30 to 60 years depending on the actual demand.
Nuclear power plants as well as nuclear waste could be preferred targets for terrorist attacks..
During the operation of nuclear power plants, radioactive waste is produced, which in turn can be used for the production of nuclear weapons.
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08-03-2011, 09:57 AM
Topic: Nuclear power station
The need of nuclear power plants is of umpteen importance in today’s age & after each decade the world demand for electricity is doubled due to increase in population & industrial growth. With fast depletion of fossil reserves the reliability of conventional power plants is on the decline.
Nuclear power plants provide large amount of power with consumption of small quantity of radio active material. The total operating cost of nuclear plant per kilo-watt hour is less when compared to coal fired thermal plant though the capital cost of is high due to heavy costs of land, foundation, nuclear reactors and nuclear fuel. There are large amounts of nuclear deposits all over the world therefore such plants can ensure continued supply of electrical energy for thousands of years. The pollution created by a thermal power plant is eliminated to a large extent by the use of nuclear power plants .when compared to hydro plants, the area required for construction of nuclear plant is reduced and the magnitude of power produced firm nuclear power plants is much higher when compared to hydro generation plants. Apart from generation of power, nuclear power plants can produce valuable fissile material which is extracted when the fuel has to be renewed. About safety of the nuclear power plant, the nuclear reactors contain only a small amount of fissionable material whereas an atom bomb has 90% fissionable material in its core.
Thus the operation of nuclear power plants is relatively safe and there is no danger of radio active leak as proper waste disposal facilities are provides in the vicinity of nuclear power plants. Thus, nuclear power generation is of utmost importance and advantageous to bridge the gap between demand and supply occurring in our country.